If Donald Trump forgives, should a court forget?

Joe Arpaio says yes, but the former lawman’s quest to erase his criminal contempt conviction will probably fail at the U.S. Court of Appeals for the Ninth Circuit, a former Justice Department attorney who handled pardons for the government and law professors who study clemency told Bloomberg Law.

After receiving a presidential pardon Aug. 25 following his July 31 conviction for violating a judicial order not to engage in racial profiling, the self-styled “America’s toughest sheriff” wants the appeals court to reverse an Oct. 19 order by the district court judge who...